The present invention generally relates to processes and compositions for making polymer latex from solid rubber or slurry of polymer, and more specifically relates to making coagulable dip grade chlorosulfonated polyethylene latex from solid chlorosulfonated polyethylene rubber. The invention also relates to compounding compositions and dip processes for making high strength chlorosulfonated polyethylene latex articles.
Adhesive grade water-based chlorosulfonated polyethylene latex is available commercially; however, it cannot be used to make thick dip articles by coagulation process. The common problems of coagulated films dipped from this type of latex are film cracking, sticky, and/or weak in cured film strength. This type of chlorosulfonated polyethylene latex is suitable for uses as adhesive or straight dip coagulation-free thin film coating. For examples, U.S. Pat. No. 5,281,638 discloses the use of chlorosulfonated polyethylene latex for adhesive applications. Commercial products CSM-450 and CSM-200 chlorosulfonated polyethylene latex made by Sumitomo Seika are also for adhesive and coagulation-free thin film coating applications. There is a need to develop new processes and compositions for making a chlorosulfonated polyethylene latex which can be used for dipping and forming thick, high strength articles by coagulation dipping process. The invention discloses compositions and methods for making chlorosulfonated polyethylene latex that are suitable for dipping articles with thickness up to more than 0.38 mm.
The use of solvent-based chlorosulfonated polyethylene rubber solution to make dip articles is common. However, the production process has several disadvantages. First, the dip process requires the removal of solvent from each individual dip article. This process is highly unfriendly to workers and environment. Secondly, the process cycle time is extremely long. For example, the cycle time for making industrial glove box gloves typically is longer than 12 hours. The invention discloses the compositions and articles made from a coagulable dip grade chlorosulfonated polyethylene latex. The invention reduces article manufacturing cycle time and eliminates the solvent related safety and environmental pollution issues. The cycle time reduction depends on composition and amount of solvent residual in chlorosulfonated polyethylene latex. Generally, the total cycle time for making a 0.38 mm thick dip article is below 3 hours if the solvent residual in chlorosulfonated polyethylene latex is below 500 ppm (parts per million).